The areas of investigation are: 1. Cytogenetic studies of human neoplastic, hematological, and congenital diseases and of members of high-risk cancer families. 2. Observations of chromosomal aberrations and teratogenic effects of mitotic inhibitors, such as, maytansine, pala, and other Phase I drugs using in vivo and in vitro techniques. 3. Characterization of human stem cells morphologically, histochemically and by electron microscope studies as well as the elucidation of the cellular kinetics and differentiation. We are using stem cells from the peripheral blood of normal subjects and patients with refractory anemias or other myelo-proliferative disorders.